Predictors of Aggression in Patients With Bipolar Disorder, Schizophrenia

The SSD group had the following diagnoses: schizophrenia; schizoaffective disorder; schizophreniform disorder; and concomitant diagnosis of schizophrenia and bipolar disorder.

Patients with schizophrenia-spectrum disorders (SSD) had higher odds of being aggressive than people with bipolar disorder with a recent manic episode, and lower odds of being aggressive than those with bipolar disorder with a recent mixed episode, according to results of a study published in Schizophrenia Research.

The investigators performed a retrospective study of de-identified data from electronic health records (EHRs) of 3322 patients seen in the medical emergency department at the Long Island Jewish Medical Center or the Health Evaluation Clinic at The Zucker Hillside Hospital between August 2011 and July 2012. The Health Evaluation Clinic admits patients who seek psychiatric treatment or who are brought in by police and/or emergency medical services for evaluation.

The investigators selected EHRs for patients with International Classification of Diseases 9th edition codes indicating SSD or affective disorders. Data extracted from the initial comprehensive psychiatric evaluation, mainly from patient self-reports, included comorbid diagnoses, recent and current homicidal thoughts and aggressive behavior, stressors at the time of evaluation, and history of abuse or neglect. Only a subset of patients answered questions about physical or sexual abuse or neglect.

The SSD group had the following diagnoses: schizophrenia, schizoaffective disorder, schizophreniform disorder, and concomitant diagnosis of schizophrenia and bipolar disorder, which the investigators considered to be schizoaffective disorder. The primary affective disorder group included the following diagnoses: bipolar disorder — most recent episode manic, bipolar disorder — most recent episode mixed, bipolar disorder not otherwise specified (NOS), major depressive disorder, depressive disorder NOS, dysthymic disorder, mood disorder NOS, and any combination of mood disorder diagnoses.

The investigators compared baseline characteristics between 2 groups: those with aggressive behavior or aggressive thoughts within the last 6 months and those without either. Multivariate regression analysis was done to determine variables independently associated with aggression. The authors compared the odds of aggression among people with SSD, bipolar disorder, and unipolar depression, using the last as a reference group. They then subdivided the SSD and bipolar disorder groups in a second regression model to study the potential differences in aggression between the schizoaffective and bipolar disorder subtypes.

The investigators classified 2402 patients as having a primary affective disorder and 920 as having an SSD. The SSD group, compared with the affective disorders group, had significantly higher rates of current homicidal/aggressive behavior (n=226/920, 24.6% vs n=226/2402, 12.5%; P <.001). The SSD group also had significantly higher rates of recent aggression to others (n=179/920, 19.5% vs n=235/2402, 9.8%; P <.001) or to property (n=76/920, 8.3% vs n=151/2402, 6.3%; P <.001).

After adjusting for age and sex, an SSD diagnosis was associated with 3.1 times the odds of aggression compared with a diagnosis of unipolar depression (95% CI [2.41, 3.87]; P <.001). Bipolar disorder was associated with 2.2 times the odds of aggression compared with unipolar depression (95% CI [1.74, 2.86]; P <.001). Conversely, a diagnosis of generalized anxiety disorder (odds ratio=0.2, 95%CI [0.05, 0.77]; P =.021) was associated with lower odds of aggression.

A second multivariate analysis showed that diagnosis of bipolar disorder — most recent episode mixed, was associated with 4.3 times the odds of aggression compared with unipolar depression (95% CI [2.58, 7.20]; P <.001); a diagnosis of schizophrenia was associated with 2.6 times the odds of aggression compared with unipolar depression (95% CI [1.90, 3.40]; P <.001); and diagnosis of bipolar disorder — most recent episode manic, was associated with 2.2 times the odds of aggression compared with unipolar depression (95% CI [1.44, 3.29]; P<.001). Conversely, a diagnosis of generalized anxiety disorder was associated with lower odds for aggression.

The researchers note that patients with depression alone tend to internalize anger, whereas those with co-occurring manic symptoms may be more prone to externalize anger and irritability. They also acknowledged that a shortcoming of the study was not systematically collecting information about substance abuse, which has been found to raise the likelihood for aggression.

Disclosures

Dr Kane has been a consultant for or received honoraria from Alkermes, Eli Lilly, EnVivo Pharmaceuticals (Forum), Forest (Allergan), Genentech, H. Lundbeck, Intracellular Therapies, Janssen Pharmaceutica, Johnson and Johnson, Neurocrine, Otsuka, Pierre Fabre, Reviva, Roche, Sunovion, Takeda, and Teva. He has received grant support from Otsuka and Janssen and has participated in Advisory Boards for Alkermes, Intracellular Therapies, Lundbeck, Neurocrine, Otsuka, Pierre Fabre, Takeda, and Teva. He is a shareholder in MedAvante, Inc., Vanguard Research Group, and LB Pharmaceuticals, Inc.

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